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Journal Articles

High-temperature oxidation failure in reactivity-initiated accidents; An Evaluation of failure criteria based on oxygen concentration from the previous NSRR experiments

Luu, V. N.; Taniguchi, Yoshinori; Udagawa, Yutaka; Katsuyama, Jinya

Nuclear Engineering and Design, 442, p.114222_1 - 114222_15, 2025/10

Journal Articles

Nacre-like MXene/polyacrylic acid layer-by-layer multilayers as hydrogen gas barriers

Auh, Y. H.*; Neal, N. N.*; Arole, K.*; Regis, N. A.*; Nguyen, T.*; Ogawa, Shuichi*; Tsuda, Yasutaka; Yoshigoe, Akitaka; Radovic, M.*; Green, M. J.*; et al.

ACS Applied Materials & Interfaces, 17(21), p.31392 - 31402, 2025/05

Journal Articles

Crystal structures and phase stability of antiferroelectric $$R$$ phases in undoped and Ca-modified sodium niobates

Aso, Seiyu*; Matsuo, Hiroki*; Yoneda, Yasuhiro; Morikawa, Daisuke*; Tsuda, Kenji*; Oyama, Kenji*; Ishigaki, Toru*; Noguchi, Yuji*

Physical Review B, 111(17), p.174114_1 - 174114_12, 2025/05

We investigate the crystal structures, phase transitions, and phase stability of undoped and Ca-modified NaNbO$$_{3}$$ through a combined analysis of high-resolution synchrotron radiation X-ray and neutron diffraction, convergent-beam electron diffraction, and density functional theory (DFT) calculations. It is demonstrated that the antiferroelectric (AFE)-$$R$$ phase is stabilized over a wide temperature range of 200 to 800 K by Ca modification, and that the NaNbO$$_3$$ is stabilized by temperature-driven isostatic pressure accompanied by lattice expansion, whereas the Ca-modified NaNbO$$_3$$ is induced by composition-induced chemical pressure along with lattice shrinkage.

Journal Articles

Scenario analysis of future nuclear energy use in Japan, 1; Methodology of nuclear fuel cycle simulator: NMB4.0

Abe, Takumi; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Asano, Hidekazu*; Takeshita, Kenji*

Progress in Nuclear Science and Technology (Internet), 7, p.299 - 304, 2025/05

Currently, much research continues on stable energy sources that do not emit CO$$_{2}$$ in order to achieve a carbon-neutral and sustainable society. Nuclear energy is one of the such sources, and various new reactors and reprocessing technologies are being developed. In order to implement the nuclear fuel cycle with these technologies, a nuclear fuel cycle simulator is required to quantitatively evaluate various quantities, such as the distribution of nuclear fuel materials and the scale of waste loading. For this purpose, NMB4.0 was developed in collaboration with Tokyo Institute of Technology and Japan Atomic Energy Agency. This code calculates the material balance of 179 nuclides including actinides and fission products (FPs) from the front-end to the back-end and simulates the nuclear fuel cycle in an integrated manner. Unlike other nuclear fuel cycle simulators, the code is capable of performing precise back-end analyses such as the number of radioactive wastes and the scale of the geological repository considering heat generation of waste package under diverse nuclear energy scenario, and is an open source code that runs on Microsoft Excel. By these features, it is possible to quantitatively study nuclear energy utilization strategies with various stakeholders. The presentation will detail the numerical model used in NMB4.0.

Journal Articles

Incorporation of boron into metakaolin-based geopolymers for radionuclide immobilisation and neutron capture potential

Niu, X.*; Elakneswaran, Y.*; Li, A.*; Seralathan, S.*; Kikuchi, Ryosuke*; Hiraki, Yoshihisa; Sato, Junya; Osugi, Takeshi; Walkley, B.*

Cement and Concrete Research, 190, p.107814_1 - 107814_17, 2025/04

 Times Cited Count:0 Percentile:0.00(Construction & Building Technology)

JAEA Reports

Conceptual study of J-PARC Proton Beam Irradiation Facility

Meigo, Shinichiro; Iwamoto, Hiroki; Sugihara, Kenta*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Saito, Shigeru; Maekawa, Fujio

JAEA-Technology 2024-026, 123 Pages, 2025/03

JAEA-Technology-2024-026.pdf:14.22MB

Based on the design of the ADS Target Test Facility (TEF-T) at the J-PARC Transmutation Experimental Facility, a conceptual study was conducted on the J-PARC proton beam irradiation facility. This research was carried out based on the recommendations of the Nuclear Transmutation Technology Evaluation Task Force of the MEXT. The recommendations state that it is desirable to consider facility specifications that can make the most of the benefits of using the existing J-PARC proton accelerator while also solving the engineering issues of the ADS. We considered facilities that could respond to a variety of needs while reducing the facilities that were not needed in the TEF-T design. In order to clarify these diverse needs, we investigated the usage status of representative accelerator facilities around the world. As a result, it became clear that the main purposes of these facilities were (1) Material irradiation, (2) Soft error testing of semiconductor devices using spallation neutrons, (3) Production of RI for medical use, and (4) Proton beam use, and we investigated the facilities necessary for these purposes. In considering the facility concept, we assumed a user community in 2022 and reflected user opinions in the facility design. This report summarizes the results of the conceptual study of the proton irradiation facility, various needs and responses to them, the roadmap for facility construction, and future issues.

JAEA Reports

Background aerial monitoring and UAV radiation monitoring technology development for emergency response and preparedness in fiscal year 2023 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Nakama, Shigeo; Sasaki, Miyuki; Ochi, Kotaro; Sawahata, Yoshiro*; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; Haginoya, Masashi*; et al.

JAEA-Technology 2024-022, 170 Pages, 2025/03

JAEA-Technology-2024-022.pdf:15.09MB

On March 11, 2011, the 2011 off the Pacific coast of Tohoku Earthquake caused a tsunami that led to the Fukushima Daiichi Nuclear Power Station accident, releasing radioactive material into the environment. Since then, Aerial Radiation Monitoring (ARM) using manned helicopters has been employed to measure radiation distribution. As a commissioned project from the Nuclear Regulation Authority, the Japan Atomic Energy Agency (JAEA) utilizes this technology for emergency monitoring during nuclear facility accidents, aiming to provide prompt results by pre-arranging information on background radiation, topography, and control airspaces around nuclear power plants nationwide. In fiscal year 2023, the commissioned project included conducting ARM around the Sendai Nuclear Power Station and preparing related information. To enhance effectiveness during emergencies, ARM and the first domestic training flight of Unmanned Aerial Vehicles (UAVs) were conducted during the FY2023 Nuclear Energy Disaster Prevention Drill. Furthermore, UAVs radiation monitoring technology was advanced by selecting UAVs and investigating their performance. This report summarizes the results and technical issues identified providing insights to improve emergency preparedness.

JAEA Reports

Aerial monitoring around TEPCO's Fukushima Daiichi Nuclear Power Station and development of radiation monitoring technology for unmanned airplanes in fiscal year 2023 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Nakama, Shigeo; Sasaki, Miyuki; Ochi, Kotaro; Nagakubo, Azusa; Sawahata, Yoshiro*; Kawasaki, Yoshiharu*; Iwai, Takeyuki*; Hiraga, Shogo*; et al.

JAEA-Technology 2024-021, 232 Pages, 2025/03

JAEA-Technology-2024-021.pdf:25.79MB

The 2011 off the Pacific coast of Tohoku Earthquake on March 11, 2011, caused a tsunami that led to the TEPCO's Fukushima Daiichi Nuclear Power Station (FDNPS) accident, releasing a large amount of radioactive material into the surrounding environment. Since the accident, Aerial Radiation Monitoring (ARM) has been used to quickly and widely measure radiation distribution. As a commissioned project from the Nuclear Regulation Authority, the Japan Atomic Energy Agency (JAEA) has continuously conducted ARM around FDNPS using manned and unmanned helicopters. This report summarizes the monitoring results for fiscal year 2023, evaluates changes in dose rate from past results, and discusses the factors contributing to these changes. Additionally, an analysis considering terrain undulation was conducted to improve accuracy for converting ARM data into dose rate. Furthermore, a method to discriminate airborne radon progeny was applied for ARM results to evaluate its impact. Moreover, to perform wide-area monitoring more efficiently, we advanced the development of unmanned airplane monitoring technology.

Journal Articles

Robustness of ferromagnetism in van der Waals magnet Fe$$_3$$GeTe$$_2$$ to hydrostatic pressure

Wang, Y.*; Zeng, X.-T.*; Li, B.*; Su, C.*; Hattori, Takanori; Sheng, X.-L.*; Jin, W.*

Chinese Physics B, 34(4), p.046203_1 - 046203_6, 2025/03

 Times Cited Count:0 Percentile:0.00(Physics, Multidisciplinary)

Two-dimensional van der Waals ferromagnet Fe$$_3$$GeTe$$_2$$ (FGT) holds a great potential for applications in spintronic devices, due to its high Curie temperature, easy tunability, and excellent structural stability in air. In this study, we have performed high-pressure neutron powder diffraction (NPD) up to 5 GPa, to investigate the evolution of its structural and magnetic properties with hydrostatic pressure. The NPD data clearly reveal the robustness of the ferromagnetism in FGT, despite of an apparent suppression by hydrostatic pressure. As the pressure increases from 0 to 5 GPa, the Curie temperature is found to decrease monotonically from 225(5) K to 175(5) K, together with a dramatically suppressed ordered moment of Fe, which is well supported by the first-principles calculations. Although no pressure-driven structural phase transition is observed up to 5 GPa, quantitative analysis on the changes of bond lengths and bond angles indicate a significant modification of the exchange interactions, which accounts for the pressure-induced suppression of the ferromagnetism in FGT.

Journal Articles

Comparative analysis of primary variables selection in modeling non-isothermal two-phase flow; Insights from EBS experiment at Horonobe URL

Kim, M.*; Lee, C.*; Sugita, Yutaka; Kim, J.-S.*; Jeon, M.-K.*

Geomechanics for Energy and the Environment, 41, p.100628_1 - 100628_9, 2025/03

 Times Cited Count:0 Percentile:0.00(Energy & Fuels)

This study investigates the impact of primary variables selection on the modeling of non-isothermal two-phase flow, by using the numerical work on the full-scale Engineered Barrier System (EBS) experiment conducted at Horonobe URL as part of the DECOVALEX-2023 project. A validated numerical model is employed to simulate the coupled thermo-hydrological behavior of heterogeneous porous media within the EBS. Two different primary variable schemes are compared in discretizing the governing equations, revealing significant difference in results.

Journal Articles

Development of on-site detection system for concealed nuclear materials

Tanabe, Kosuke*; Komeda, Masao; Toh, Yosuke; Kitamura, Yasunori*; Misawa, Tsuyoshi*

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 67(3), p.198 - 202, 2025/03

no abstracts in English

Journal Articles

Massive Dirac magnons in the three-dimensional honeycomb magnetic oxide FeTiO$$_3$$

Chung, J.-H.*; Kwangwoo, S.*; Yokoo, Tetsuya R.; Ueta, Daichi*; Imai, Masaki; Kim, H.-S.; Kiem, D. H.; Han, M. J.*; Shamoto, Shinichi

Scientific Reports (Internet), 15, p.5978_1 - 5978_10, 2025/02

 Times Cited Count:0 Percentile:0.00(Multidisciplinary Sciences)

Journal Articles

Integrity evaluation of boundary function of main components in nuclear plants during severe accidents

Tsukimori, Kazuyuki; Yada, Hiroki

Journal of Pressure Vessel Technology, 147, p.031901_1 - 031901_9, 2025/00

 Times Cited Count:0

After the accident at the Fukushima Daiichi Nuclear Power Plant, very strict safety measures were implemented for nuclear power plants in Japan. It thus becomes a crucial issue if the safety of a plant is maintained or not at beyond design basis events. In this study, head plates and bellows were examined as components that compose the parts of the boundary of vessels that contain the primary coolant of a prototype fast breeder reactor. The behaviors of buckling, post-buckling deformation, and penetration failure, that is, loss of boundary function of these components with increasing pressure were investigated. The series of this research program started in FY2013 and the research proceeded step by step. The new result in this paper is the application of the proposed criteria to head plates and bellows, and a conservative estimation of penetration failure of these components is obtained.

Journal Articles

New insight on the thermal impact on cementitious materials due to high-temperature with water supply; Continuous expansive spalling in water

Miura, Taito*; Miyamoto, Shintoro*; Maruyama, Ippei*; Aili, A.*; Sato, Takumi; Nagae, Yuji; Igarashi, Go*

Case Studies in Construction Materials, 21, p.e03571_1 - e03571_14, 2024/12

 Times Cited Count:0 Percentile:0.00(Construction & Building Technology)

Journal Articles

Application of indentation technique to material degradation evaluation in the mercury target vessel for spallation neutron sources

Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi

Jikken Rikigaku, 24(4), p.212 - 218, 2024/12

Irradiation damage is one of the main factors determining the lifetime of the mercury target vessel for spallation neutron source in J-PARC. To understand material degradation of the used vessels, it is planned to conduct an evaluation using inverse analyses with indentation tests on the structural materials of the used vessels and numerical experiments. This evaluation technique was applied to two kinds of ion-irradiated materials with different displacement damage doses, in which the irradiation condition was simulated. It could be confirmed that the ultimate strength increased, and the total elongation decreased with increasing irradiation. These trends are like the material degradation behaviors which have been reported by using small specimen's tensile tests.

Journal Articles

Enhanced cryogenic mechanical properties of heterostructured CrCoNi multicomponent alloy; Insights from ${it in situ}$ neutron diffraction

Naeem, M.*; Ma, Y.*; Knowles, A. J.*; Gong, W.; Harjo, S.; Wang, X.-L.*; Romero Resendiz, L.*; 6 of others*

Materials Science & Engineering A, 916, p.147374_1 - 147374_8, 2024/11

 Times Cited Count:2 Percentile:63.37(Nanoscience & Nanotechnology)

JAEA Reports

Reports on research activities and evaluation of advanced computational science in FY2023

Center for Computational Science & e-Systems

JAEA-Evaluation 2024-001, 40 Pages, 2024/10

JAEA-Evaluation-2024-001.pdf:1.46MB

Research on advanced computational science for nuclear applications, based on "the plan to achieve the medium- and long-term goal of the Japan Atomic Energy Agency", has been performed by Center for Computational Science & e-Systems (CCSE), Japan Atomic Energy Agency. CCSE established a committee consisting of external experts and authorities which evaluates and advises toward the future research and development. This report summarizes the results of the R&D performed by CCSE in FY2023 (April 1st, 2023 - March 31st, 2024) and their evaluation by the committee.

Journal Articles

Effect of radon inhalation on murine brain proteins; Investigation using proteomic and multivariate analyses

Naoe, Shota*; Tanaka, Ayumi*; Kanzaki, Norie; Takenaka, Reiju*; Sakoda, Akihiro; Miyaji, Takaaki*; Yamaoka, Kiyonori*; Kataoka, Takahiro*

Acta Medica Okayama (Internet), 78(5), p.387 - 399, 2024/10

Journal Articles

Biofilm-mediated interactions between plastics and radiocesium in coastal environments

Battulga, B.; Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Otosaka, Shigeyoshi*; Koarashi, Jun

Environmental Science and Pollution Research, 31, p.60080 - 60092, 2024/10

A ubiquitous distribution of plastic debris has been reported in aquatic and terrestrial environments; however, the interactions between plastics and radionuclides and the radioactivity of environmental plastics remain largely unknown. Here, we characterize biofilms developing on the surface of plastic debris to explore the role of plastic-associated biofilms as an interaction medium between plastics and radiocesium ($$^{137}$$Cs) in the environment. Biofilm samples were extracted from plastics (1-50 mm in size) collected from two contrasting coastal areas in Japan. The radioactivity of plastics was estimated based on the $$^{137}$$Cs activity concentration of the biofilms and compared seasonally with surrounding environmental samples (i.e., sediment and sand). $$^{137}$$Cs traces were detected in biofilms with activity concentrations of 21-1300 Bq kg$$^{-1}$$ biofilm (dry weight), corresponding to 0.04-4.5 Bq kg$$^{-1}$$ plastic (dry weight). Our results reveal the interaction between $$^{137}$$Cs and plastics and provide evidence that organic and mineral components in biofilms are essential in $$^{137}$$Cs retention in environmental plastics.

Journal Articles

Dynamics and functions of microbial communities in the plastisphere in temperate coastal environments

Battulga, B.; Nakayama, Masataka; Matsuoka, Shunsuke*; Kondo, Toshiaki*; Atarashi-Andoh, Mariko; Koarashi, Jun

Water Research, 264, p.122207_1 - 122207_12, 2024/10

 Times Cited Count:7 Percentile:87.53(Engineering, Environmental)

Growing attention has been given to microbial attachment and biofilm formation on microplastics (MPs; sizes: $$<$$5 mm) in the environment. Here, we explore the microbial communities in the plastisphere to improve our understanding of microbial ecology as well as their impacts on aquatic ecosystems. Using the amplicon sequence of 16S and ITS genes, we identified bacterial and fungal community composition and diversity on MPs, surface waters, bottom sediments, and coastal sands in two contrasting coastal areas of Japan. Significantly different microbial diversity and taxonomic composition were detected depending on sample types and research sites. This research highlights the microbial metabolic functions in MP-associated biofilm, which could be the key to uncovering the true impact of plastic debris on the global ecosystem.

943 (Records 1-20 displayed on this page)